Hydraulic power system



Aug. 21, 1956 F. H. KIND HYDRAULIC POWER SYSTEM 5 Sheets-Sheet 1 FiledApril 22, 1954 1956 F. H. KIND HYDRAULIC PQWER SYSTEM 3 Shets-Sheet 2Filed April 22, 1954 U U H Aug. 21, 1956 K 2,759,455

HYDRAULIC POWER SYSTEM Filed April 22, 1954 v 3 Sheets-Sheet 3 IN V ENTOR.

United States Patent HYDRAULIC POWER SYSTEM Frederick H. Kind, Racine,Wis., assignor to Racine Hydraulics & Machinery Inc., Racine, Wia, acorporation of Wisconsin Application April 22, 1954, Serial No. 424,979

8 Claims. (Cl. 121-20) This invention relates to a hydraulic system andmore particularly to a high speed reversible hydraulic power systemembodying a new and improved reversing valve mechanism.

A general object of the invention is to provide a new and improvedhydraulic power system embodying a reversing valve mechanism and a highspeed hydraulic tamping machine, hammer or other work device having acylinder provided with a piston to be rapidly reciprocated.

Another object is to provide a hydraulic system embodying a source ofhydraulic fluid under pressure, a tool having a piston and cylinderdevice, the piston being spring urged in one direction andintermittently hydraulically driven in the opposite direction, areversing valve for controlling the supply of fluid to one end of thecylinder and the return of it therefrom through a plurality of conduitsin parallel between the valve and cylinder, and means for causingintermittent progressive movement of the fluid in one conduit towardsthe cylinder and in another conduit away from the cylinder to preventthe fluid from over-heating.

Another object is to provide a new and improved-reversing valvemechanism embodying a main valve for controlling fluid flow to and froma work piston, and a shiftable pilot valve for controlling reciprocationof the main-valve, the shifting movement of the pilot valve'b'etweenoperative positions being initiated by and during movement of the mainvalve to'facilitate maximum utili zation of hydraulic power for causingrapid reciprocation of the main valve and-work piston.

Another object is to-provide a'valve mechanism of the type describedabove embodying a main valve, spring urged in one directionand-hydraulically driven in the reverse direction, and a shiftable pilotvalve for controlling the hydraulic movement of the main valve, thepilot valve being mechanically connected to the main valve andreleasably held in operative positions by a detent device-of a loadandfire device prior to being rapidly shiftedbythe load and firedeviceactuated by and during the main valve movements.

Another object is to provide a valve mechanism of the type describedabove provided with means for varying the rate of reciprocation of themain valve.

Further" objects and advantages will become apparent from the followingdetailed'description taken in connection with the appended'drawings'inwhich:

Fig. 1 is a view of a preferred form of'theinv'en'tion showing a systemwith the valve and a work device in central section'andwith the parts inthe positions assumed when the main valve connects the work device to asource of hydraulic fluid under pressure and just prior to the shiftingof the main valve into the position illustrated in Fig; 2; I

Fig. 2 is a view similar to Fig. l'but showing the relation of'the' mainvalve, pilot valve'an'd work device parts when themai'n valveisposition'e'd' for connecting the 2,759,455 Patented Aug. 21, 1956 2work device to drain just prior to the shifting of the main valve intothe position illustrated in Fig. 1;

Fig. 3 is an elevational view of the reversing valve looking at theright hand end of the valve in Fig. 1; and

Fig. 4 is a sectional view taken along line 44 of Fig. 1.

While this invention is susceptible of embodiment in many diflerentforms, there is shown in the drawings and will be herein described indetail an illustrative embodiment of the invention with theunderstanding that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the embodiment illustrated. The scope of theinvention will be pointed out in the appended claims.

In the preferred embodiment of the invention illustrated in thedrawings, a reversing valve, generally desigdated 10 is connected in asystem comprising a hydraulic fluid source 11, a pump 12, and a workdevice in the form of a tamping tool 15.

The tamping tool embodies a casing 16 having a cylinder 17 thereincommunicating at it'sup'per or pressure end 18 with a pair of conduits13 and 14 which extend in parallel arrangement to the reversing valve. Apiston 19 is slidable in the cylinder and is continuously urged to wa'rdthe pressure end 1 8 by a coiled sprin'g' 20"positioned in the lower endof the cylinder. A cylindrical piston rod 21 fixed to the piston,- isslidable in a bore 22 in the casing and has a free end 23 operable as ahammer for intermittently striking a tool member 24' slidable in a bore25 in the lower end of the casing.

The valve 10 is adapted alternately to'adniit hydraulic fluid underpressure tothe upper end 18 of cylinder 17 to drive the pistondownwardly to cause a hammer-like blow of the rod 21 against the toolmember 24, and to permit return flow of the fluid out of the cylinder asthe spring 20 returns the piston upwardly in cylinder 17.

As shown'in Figs. 1 and 2, the valve 10 comprises a casing having acentral part 26, a' left end" plate 27 and a right end member 28; Acylindrical main valve member 29 is slidably positioned in a cylindricalsleeve 30 fixed in a main valve bore 31 H Main valve member 29 isprovided with lands 32, 33 and34 defining annular grooves 35'and-SG'therebetweenL A plurality of ports 37-, 38 and 39 in the sleeve30con= nect with annular grooves 41', 42 and 43' in" the central part-26of the casing. An annular casing groove 40 surrounds the left' hand endof the sleeve 30 and connects with an annular passage 40' which, asdescribed hereinafter, communicates with a drain line leading tothe-source 11. A passage 44 in the casing communicates with the conduits13 and 14 and with'the gro'ove42' which turn is in constantcommunication with sleeve port 38. An inlet-passage 45 in the casingcommunicate's with annular groove 43 and is also shown connected to thepump 12 by a conduit 5. A passage 46in the casing communicates withannulargroove 41' and is also shown connected to the source 11- by adrain conduit 6; A conduit 7 extends from the source 11' to the inle'tof the pump 12.

Rapid reciprocation of the-main valve member 29"between a forwarderin'let position as illustrated in Fig. 1 and a reverse or drain positionas shown in Fig.- 2 alternately connects'tool 15 to a sourceof hydraulicfluid under pressure or to drain toimpart arapid reciprbcato'ry motionto hammer 23 and tool=member 24; When the main valve member 29 is intheinlet position (Fig. 1) the upper end 18 of the tool cylinder 17 issuppliedwith fluid under pressure flowing from the'pump 12 throughconduit 5, inlet passage 45, groove 43, ports 39, groove 36, port 38,groove 42, passage 44 and parallel conduits 13 and 14 and the piston 19is driven rapidly down against the force of spring 20. The main valvemember,

3 when in the drain position shown in Fig. 2, connects the upper end ofcylinder 17 to drain; thus allowing spring 20 to move piston 19 upwardlyin the cylinder to force hydraulic fluid back through conduits 13 and14, passage 44, groove 42, port 38, groove 35, ports 37, groove 41,drain passage 46 and conduit 6.

Preferably annular rubber collars 47 are positioned on bosses 48 and 49on the casing end plate 27 and end member 28, respectively, to stop andcushion the main valve member at the ends of its strokes whenreciprocated as hereinafter described.

The main valve member 29 is spring urged to its drain position as shownin Fig. 2 by means of a coiled spring 51 which is compressed between theboss 48 and a transverse wall 50 in the valve member. At its left handend the spring is supported by a tube 52 threadably received in boss 48and at its right hand end on a nut 53 which bears on a flanged sleeve 54and threadably secures a cylindrical stem 55 to transverse wall 50 ofthe main valve. A passage 56 in tube 52 receives fluid which may leakinto the main valve member and connects with a passage 57 communicatingwith the annular chamber 40. The chamber 40 communicates with the groove40 connecting with the left end of main valve sleeve 30 and the chamber40' connects to drain through a passage 57, a conduit 9 and the conduit6. Preferably ports 50' are provided in valve wall 50 to prevent abuild-up of pressure to the right of the wall.

Means is provided to move the main valve member hydraulically from theposition shown in Fig. 2, to which it is moved by the spring 51, to itsinlet position, as shown in Fig. 1. The valve stem 55 is slidable in abore 58 in casing member 28, which bore is enlarged at 59 and carries abushing 60. Enlarged bore 59 provides a cylinder for a piston formed bya shoulder 61 adjacent a reduced portion 55' of the valve stem. It isthe supply of hydraulic fluid under pressure to and the release of fluidfrom this cylinder by a pilot valve mechanism which, aided by the spring51, causes the automatic reciprocation of main valve member 29.

The pilot valve mechanism comprises a spool type valve member 62slidable in a cylindrical sleeve 63 fixed n a bore 64 in casing member28. The valve member is provided with collars 65, 66 and 67 definingannular grooves 68 and 69 operably associated with sleeve ports 70, 71and 72 and annular casing grooves 74 and 75 for passing fluid controlledby the pilot valve. The sleeve 63 extends through a bore in casing part26 to leave an annular passage 76 between the valve inlet passage 45 andports 70. The end of the sleeve is closed by a plate 63' and has aresilient plug 79 for cushioning the reversmg of the valve member 62 atthe left hand end of its reciprocatory movement. The valve member 62 hasa hollow bore 62a to permit escape of air and any leakage fluid from theend of the sleeve containing plug 79.

In the position shown in Fig. 1, fluid under pressure from the inletpassage 45 passes through passage 76, ports 70, groove 68, ports 71 andgroove 74 to a passage 77 which connects with cylinder 59 and the piston61 is moved to the left against the action of spring 51 until the mainvalve reaches the position shown in Fig. 1. The pilot valve member 62 isthen shifted (by means hereinafter described) to the position shown inFig. 2, and during the shifting motion fluid in the cylinder 59 exhauststhrough passage 77, groove 74, ports 71, groove 69, ports 72, groove 75,a passage 78, and drain passage 46 and valve member 29 moves to theposition shown in Fig. 2 under the influence of spring 51.

In the preferred form of the invention, the pilot valve member 62 ismechanically connected to the main valve stem 55 by means including aload and fire device so that as the main valve member reaches each endof its stroke the pilot valve is automatically shifted from one positionto the other in which it causes reversal of the main valve member. Theconnecting means comprises an arm 82 secured at its lower end to mainvalve stem portion 55 as by nuts 83 and has at its upper end a hole inwhich a sleeve 84 is fixed. This sleeve is slidable between spacedabutments 85 and 86 fixed to a stem 87 carried by the pilot valve member62 and extending therefrom in a substantially parallel spaced relationto main valve stem 55. Sleeve 84 is provided with cylindrical springconfining extensions 88 and 89 in engagement with adjacent ends ofcoiled springs 98 and 91 which surround the pilot valve stem 87 betweenthe abutments 85 and 86 respectively and the slidable sleeve 84. Thesprings 90 and 91 are so designed that they expand as shown in Figs. 1and 2 and can alternately 'be compressed within the extensions 88 and 89to permit engagement of the ends of the extensions with the abutments 85and 86, after the springs are compressed, to positively actuate thepilot valve member.

In order to obtain heavy hammer blows on the tool member 24 thereversing valve is adapted to shift the main valve member 29 rapidlyback and forth between its operative positions so that for any givenspeed of reciprocation the valve member supplies a maximum amount offluid to the tool 15 by opening the fluid ports quickly to their wideopen positions, thus giving the greatest possible transmission of powerto the tool. To accomplish this the pilot valve is also adapted toremain in one position as long as possible and then shift rapidly to theother.

As shown in the drawings, the load and fire device embodies a detentmechanism for releasably holding the pilot valve member in either of itsoperative positions. This mechanism comprises a cylindrical detentcollar 92 fixed around a portion 62 of pilot valve member 62 and againsta shoulder formed between portion 62' and an integral extension 62"which forms a part of the pilot valve stem 87. A central circumferentialrib 93 extends outwardly from the collar and is provided with oppositelyfacing surfaces 94 and 95 each alternately engageable with an expandableO-shaped coil spring 96 positioned around the detent collar adjacent oneface of rib 93. The detent collar is slidable within a cylindricalbushing 97 mounted in the casing 28 and having two parallelcircumferential ribs 98 defining an annular slot 99 opening toward therib 93 and, serving to confine the coil spring 96 against movementlongitudinally of the casing while permitting it to expand to pass overthe rib 93.

The pilot valve is arranged to be shifted during the end limits of themain valve movement. The Figs. 1 and 2 illustrate the relative positionsof the main valve and pilot valve immediately prior to shifting of thepilot valve by movement of the main valve into the end limits of itsinlet and drain positions, respectively. As the main valve member movesto the inlet position as illustrated in Fig. 1, sleeve 84 moves to theleft first to compress the spring 90 and coil spring 96 acts againstface 94 of rib 93 to prevent the pilot valve from shifting. Continuedmovement of the main valve beyond the position shown in Fig. 1 causesspring confining extension 88 to positively engage abutment 85, and ineflfect, to bump the pilot valve member in the direction the main valvemember is moving. This positive engagement causes coil spring 96 toexpand over rib 93 and trigger the load and fire device to release theforce of compressed spring 90 which is of suffieient strength tothereafter quickly shifit the pilot valve into the position shown inFig. 2. 'llhis allows the main valve to shift to its spring-urgedreverse position of Fig. 2. Movement of the main valve to the positionillustrated in Fig. 2 first compresses spring 91 and then causes theother spring confining extension 89 to bump abutment 86 again snappingloop spring 96 over rib 93 to trigger the load and fire device andrelease the force of compressed spring 91 to cause shifting of the pilotvalve into the position shown in Fig. 1 and allow flow of hydraulicfluid into cylinder 59 to drive the main valve into the inlet position.

To aid in cushioning the pilot valve at its other limit of movement, acoiled spring 80 is placed between valve collar 67 and a disk 81slidable on valve portion 62. As shown in Fig. 1, the disk 81 engagesrib 98 tocushion the pilot valve member at the right hand end of itsstroke.

Normally, with a hydraulic system in which a reversing valve controlsthe flow of fluid through a relatively long conduit to only 'one end ofa cylinder that has a piston returned by a spring, a substantial part ofthe column of hydraulic fluid in the conduit continuously recipro'caltesin the cylinder and conduit and is not replaced with other fluid. Thetrapped fluid thus becomes excessively hot. To .avoid such trapping andexcessive heating of the fluid the invention provides means, associatedwith passages 13 and 14, to cause circulation of hydraulic fluid in thecircuit during operation of the reversing valve. As illustrated in Figs.1, 2 .and 4, conduits '13 and 14 are formed in part by connecting boresin plates 110, 1 11, and 1 12 forming the upper end of the casing of thetool '1 5 where conduit '18 is provided with a nozzle 1'00 directeddownwardly or towards the cylinder 17 and conduit '14 is provided with asimilar nozzle 103 directed upwa-rd'lyor away from the cylinder 17.Nozzle 3100 is formed by adownwardly tapered and diminishing bore 101 inthe plate 1111 which produces an annular shoulder 102 tending toobstruct flow of fluid out of the cylinder through conduit 16. Nozzle103 is formed by a similar upwardly tapered and diminishing bore 104 inthe plate 111 which produces an annular shoulder 105 tending to obstructflow of fluid towards the cylinder through conduit 14. Thus it isapparent that although conduits 13 and 14 provide parallel passagesbetween the reversing valve and the tool 15, and are otherwise the same,conduit 13 allows flow of a larger volume of fluid to cylinder 17 thanconduit 14 does each time the cylinder is connected by the valve toreceive fluid and conduit 13 allows the passage of a lesser volume offluid from the cylinder than conduit 14 does when the piston 19 isreturned upwardly by spring 20. This prov-ides an intermittent butuni-direc-' tional circulation of fluid in the parallel conduits,cylinder and valve so that the fluid fed :to the-cylinder iscontinuously changed to prevent the fluid from over-heating and alsoallows any air in the connecting lines to escape, which would otherwisebe trapped in the lines.

Means may be provided for varying the rate of reciprocation of the mainvalve (and, thereby, the tool piston 19) by controlling the rate offluid flow through passage 78. As shown in Figs. 1 to 3, a cylindricalvalve 106 is threadably received in a bore in casing member 28 extendingacross passage 78 and is provided with a diametrically extending port107 which forms a part of the passage. The rate of flow may be varied byrotating the valve to vary the port opening in communication with fluidin the passage. The valve has a screw driver slot 108 to f-acili tateadjustment of the valve.

I claim:

1. A hydraulic system comprising; in combination, a source of hydraulicfiuid under pressure, an operating device having a cylinder and a pistonslidable therein and spring urged in one direction and periodicallyhydraulically driven in the reverse direction, a reversing valve forcontrolling the flow of fluid to and from said cylinder to drive thepiston repeatedly against the action of said spring including, a mainvalve member having spring means for urging it to a drain position,means including a pilot valve shifta'ble between first and secondpositions for hydraulically controlling reciprocation of the main valvemember, and means responsive to the movement of the main valve memberfor shifting the pilot valve to reverse movement of the main valvemember, means defining a pair of conduits communicating between thereversing valve and cylinder, and means in one of said conduits forpartly obstructing fluid flow in one direction 6 only in said conduit toprovide intenmittent unidirectional circulation of fluid in the conduitsduring reciprocation of said piston.

2. A hydraulic system for operation by a hydraulic fluid under pressurecomprising; in combination, an operating device having a cylinder and apiston slidable therein and spring urged in one direction andperiodically hydrau 'l-ically driven in the reverse direction, areversing valve comprising a casing, a main valve member slidabletherein between an inlet position for feeding a hydraulic fluid underpressure to the cylinder and a drain position [for connecting thecylinder to drain, spring means for urging the main valve member towardits drain position, means including a pilot valve for hydraulicallydriving the main valve member toward its inlet position, meansresponsive to the movement of the main valve member tor shitting thepilot valve to reverse movement of the main valve member including aload and fire device connected between said main valve member and .thepilot valve, and means defining a plurality of conduits communicatingbetween the main valve member and said cylinder, at least one of saidconduits having means for retarding fluid flow 'in one direction only insaid conduit during reciprocation of the columns of fluid in theconduits to reciprocate said piston to provide some intermittentuni-directional circulation of fluid in the conduits to avoid excessiveheating .of the fluid.

3. A hydraulic system for operation by a hydraulic fluid under pressurecomprising; in combination, an operating device having a cylinder and apiston reciprocable therein spring urged in one direction andperiodically hydraulically driven in the reverse direction, a reversingvalve operable for alternately feeding hydraulic fluid to one end of thecylinder and exhausting it from said end of the cylinder to drain, meansdefining first and second conduits communicating between the valve andcylinder, said first conduit having an internal tapered portionterminating to form a shoulder facing fluid flow from said cylinder, anda tapered portion in said second conduit terminating tO fOIII1 ashoulder facing fluid flow to said cylinder, said first conduit allowingflow of a larger volume of fluid to said cylinder than the secondconduit when the cylinder is connected 'by the valve to a source ofhydraulic fluid under pressure and passage of a lesser volume of fluidfrom the cylinder than the second conduit when the cylinder is connectedby the valve to drain thereby providing some uni-directional circulationof fluid through the conduits during reciprocation of said piston.

4. A hydraulic system for operation by a hydraulic fluid under pressurecomprising; in combination, an operating device having a cylinder and apiston reciprocable therein and spring urged in one direction andperiodically hydraulically driven in the reverse direction, a reversingvalve operable for alternately feeding a pressure fluid to and exhausingit from one end of the cylinder, means defining a plurality of conduitscommunicating between the valve and cylinder, at least one of saidconduits having an internal tapered portion forming a shoulder facingfluid flow from said cylinder to provide some uni-directionalcirculation of fluid in the system during reciprocation of the piston inthe cylinder.

5. A hydraulic system comprising; in combination, an operating devicehaving a cylinder and a piston reciprocable therein, means continuouslyurging the piston in one direction, and means periodically hydraulicallydriving the piston in the reverse direction comprising a source ofhydraulic fluid under pressure, a reversing valve operable foralternately supplying said fluid to and exhausting it from one end ofthe cylinder, and means defining a plurality of conduits communicatingbetween the reversing valve and cylinder, at least one of said conduitshaving means for obstructing fluid flow in one direction in said conduitto provide some uni-directional circulation of fluid in the systemduring reciprocation of the piston in the cylinder.

6. A hydraulic system comprising; in combination, an operating devicehaving a cylinder and a piston reciprocable therein, means forintermittently supplying hydraulic fluid under pressure to andexhausting it from one end of the cylinder, means defining a pair ofconduits communicating between the cylinder and said fluid supply means,at least one of said conduits having means operable to cause less flowof fluid in one of said conduits in one direction than in the otherdirection during continuous reciprocation of the piston in the cylinder.

7. An automatic reversing valve mechanism for controlling the flow ofhydraulic fluid to and from a high speed impact tool member comprising;in combination, a casing, a main valve member reciprocable in a bore insaid casing between a forward position in which a hydraulic fluid underpressure is connected to said impact member and a reverse position inwhich the impact member is connected to drain, a spring positioned insaid bore bearing against one end of the main valve member and operableto urge the main valve member to its reverse position, a valve stemconnected to said main valve memher, a portion of said valve stem beingreciprocable in a bore of the casing and having a shoulder operable as apiston in a cylinder formed by an enlargement of the bore, a pilot valvemember reciprocable in another bore in said casing between a firstposition wherein fluid under pressure is directed into the cylinderagainst the shoulder to drive the main valve member to its forwardposition and a second position wherein the cylinder for the valve stemshoulder is connected to drain, means operable by the main valve memberfor shifting the pilot valve member between its first and secondpositions including a stem connected to said pilot valve member, an armconnected to said main valve stem for movement therewith and having oneend slidably mounted on said pilot valve stem for movement betweenspaced abutments alternately engageable by said arm during the endlimits of movement of the main valve member, a spring positioned betweensaid arm and each abutment, and detent means including a detent collarwith an outwardly-extending rib fixed to the pilot valve member and anO-shaped coil spring confined against movement with the pilot valvemember and alternately engageable with opposite sides of said rib forreleasably holding said pilot valve member in either of its positions.

8. A reversing valve mechanism adapted for continuously reversing theflow of hydraulic fluid therethrough comprising; in combination, acasing, a main valve member reciprocable in a bore in said casingbetween a forward position and a reverse position, spring means forurging the main valve member to its reverse position, piston andcylinder means operable for driving the main valve member to the forwardposition, a pilot valve member reciprocable in another bore in saidcasing between a first position wherein fluid under pressure is directedinto the piston and cylinder means to drive the main valve member towardits forward position and a second position wherein the piston andcylinder means is exhausted, means for cushioning the pilot valve memberat the end limits of its stroke, means operable by the main valve memberfor shifting the pilot valve member between its first and secondpositions including a stem connected to said pilot valve member, meansconnected to said main valve member for movement therewith and fixed toa sleeve slidably mounted on said pilot valve stem for movement betweenaxially spaced abutments fixed to said stein for alternate engagement bysaid sleeve during the end limits of the main valve member movements, acoiled spring encircling said pilot valve stem between the sleeve andeach abutment, a detent mechanism for releasably holding said pilotvalve member in each of its positions and including a detent collarfixed to said pilot valve member and having a rib extending outwardlytherefrom, said detent collar being slidable in a bushing fixed to saidcasing and having an annular slot opening toward said rib, and anO-shaped coil spring confined in said annular slot for alternateengagement with opposite sides of said rib and operable for releasablyholding the pilot valve member in either of its positions.

References Cited in the file of this patent UNITED STATES PATENTS1,443,200 Adams Jan. 23, 1923 1,704,238 Barks Mar. 5, 1929 FOREIGNPATENTS 274,166 Great Britain July 7, 1927 623,478 Great Britain May 18,1949

